(IMAGES-614) Add Windows 2012r2/2016 Core defs
(IMAGES-614) Add Windows 2012r2/2016 Core defs

Add Beaker Host Generator definitions for:
1. Windows-2012r2-core-x86_64
2. Windows-2016-core-x86_64

Although these platforms are now on vmpooler, pipelines can't use them
without hostgenerator definitions.

puppetlabs/beaker-hostgenerator